I am guessing here, but maybe the focus point may struggle finding a sufficient contrast to lock onto. I know I find I have to work at with landscape shots in particular. We were out for a drive to the coast today and there is a few shots between me and the wife that are out of focus due to lack of contrast. Really should have gone to single shot mode.

I could really do with a second body one for action/wildlife photos and the bigger zoom and one for landscape shots, swapping lenses and settings is annoying me.

Well took my 7D out today again, and I was wondering: can a camera work just fine with One Shot but a bit off when using AI Servo or is that just crazy? I have made a shot of a sitting seagull and it was just fine, but a picture I took of a couple of flying geese seemed a bit off. The camera had a clear shot and all the time in the world to track them, so it should have been spot on.

Tracking focus is one of the hardest things for any camera to do, birds in flight being a good example of that. Take a series of shots, and you will get some in decent focus. Don't expect 100% of them to be perfect.

Well I have taken a closer look at some images. And it seems as though the focus seems to lie a bit in front of the subject when shooting my 100-400 at 400. But with my test shots on a tripod it seemed spot on. Could it be AF is off a bit when using Servo (front focussing) on 400mm with a subject that is farther away? The test with the tripod was pretty close range obviously. I know I have Micro Adjustment available, but what would you advise me to do? How can I get the best results with this option?

like I mentioned in an earlier post, I need +3 .if you post a picture it may help.here is one of mine, prior to adjusting front focus.I was focusing on duck , but grass in front is more in focus, doesn`t look like much but its the best example I got.

I got the feeling this is it. Will try to post some examples but I have the same feeling with my pictures. So what would be the best way to decide how much + I need? If I understand correctly I need to use + for correcting front focus right?

I have tried with charts indoors and its didn`t work for me, I stand at an angle alongside a fence or a wall and focus on a point further along and take a picture. When you look at on a monitor typically the area in front of focus point is in focus.Keep the angle reasonable shallow, ie stand 1-2 m from wall and focus on a point or mark further down.

Thanks for the tips. Will try to work this out as soon as I get a bit of time. Can you tell me the following: I read that micro adjusting might not solve the problem, but will just move the problem elsewhere (say: at 400mm it will be sharp at a distance, but now it will be out of focus when the subject is closer, or will be out of focus on say 100mm). Is this true? Because if that might be the case, then I should send the camera to Canon to have them recalibrate it altogether.

Both pictures have been severely sharpened with DPP and still don't show me that crisp sharpness that I did get with my 40D and my 100-400. I can upload more examples if needed. Could it be that the 18MP RAW files will never be as sharp when looking at 100% as my 10MP RAW files from my old 40D?

I don`t really know, so take this with a grain of salt. I am making this up as I am going along.

it appears that there is some front focus, suggest you use the 100-400L at aperture of 7.1 . It`s what I have seen many other use this lens at, gives you more room for error and lens is sharper there. Why, because a crop sized sensor of 10MP will not be as sensitive to lens quality and more forgiving that 18mp. ie pixelsize is smaller on 7D.

Why not just put the micro focus on +3 and go and take a hundred shot and see how they go. If its not good try a bit more or less.

I don`t have any issue with the micro adjust throwing out the rest of the focusing on my 70-300L, which is on +3 all the time.

The only issue I have is with my 50mm 1.8, I don`t like using, it front or back focuses as the distance to subject changes. Its annoying on many levels, but not going to get into on the thread.

here is a 100% crop , I do the min amount of work in LR4 that I can get away with.LR4-5242 by maxjj, on Flickr

Well that sure looks a lot sharper when comparing your 100% crop with mine. I think I will do as you say: try a load of shots with +3 and see what happens. Gonna try this same approach with my 70-200 if I run into trouble with that one too. So far haven't taken any shots with that one on my 7D yet, but maybe when the weather gets better I can take some tennis shots.

oldCarlos wrote:

Agree with Max about stopping down a tad. Also are you using `spot` focus, is image stabilisation turned on @ fast shutter speeds & is in-camera noise reduction on?

Well let me see:

1. I was using Spot2. IS was turned on, with a shutter time of 1/8003. In-camera high ISO noise reduction is on, but on the standard medium setting

Anything I should try and play around with there? Or are these settings alright?

On your photo of the Coot, where on the head were you focusing? You're using spot, which shrinks the AF point and in theory that could allow for more accurate focus... But let's assume you stuck your Spot AF point over the "meaty" part of the bird's head. A Coot is black and contrastless, so unless you've got focus-priority set for the AF/drive algorithm, your shutter is going to release in Servo even if AF is not "confirmed" and it's mid-search while trying to find contrast on that black spot you've pointed at.

If you're using spot AF, you really have to watch out for low-contrast areas on your subject. I've been burned many times before that way... I found that using the "expanded" AF points, or even just a normal-sized one is often the best bet. Once I sorted out my AF points and technique issues, I found that AFMA wasn't necessary, even for my slightly-wonky 50/1.8 that loved to backfocus in spot AF.